Simulation of the annual thermal and hydrological cycle in Mexico

Abstract

A nonlinear monthly water balance model for twelve hydrologic zones of Mexico is presented. The balance thermal energy equation applied to a thin soil surface layer and the water balance equation with maximum soil moisture deficit of 112.5 mm are coupled through the soil temperature and the soil moisture deficit. The model has five parameters. Input data are surface air relative humidity, cloudiness, surface air temperature, surface wind speed, precipitation, surface albedo, and the short wave radia- tion at the surface with clear sky. The model gives an estimate of the monthly surface and subsurface runoff, the soil moisture, the net radiation, the sensible and latent heat, the soil temperature and the annual dryness index. The computed total annual runoff (surface plus subsurface) agrees with the map of observed values. The computed monthly total runoff values show monthly variations similar to those observed in rivers of each hydrological zone. The maps of soil surface temperature and moisture availability computed for January and July show some similarities with the maps from the National Center for Environmental Prediction large-scale reanalysis.